Fatal amebic encephalitis caused by Balamuthia mandrillaris in an immunocompetent host: a clinicopathological review of pathogenic free-living amebae in human hosts.

Encephalitis caused by Balamuthia amebic species is an increasingly recognized chronic granulomatous infectious process that may affect both immunocompetent and immunocompromised individuals. The course of the disease is insidious but fatal in most cases, mainly because of delayed diagnosis, difficulty in isolation and/or identification of the organism, and lack of well-established therapeutic regimens. We report a fatal case of Balamuthia mandrillaris chronic granulomatous encephalitis in an immunocompromised host and review the clinicopathologic characteristics of infections caused by this and other pathogenic free-living amebae.